Typically, when an ultrasound imaging system is used in a medical application for imaging a patient's body, the ultrasound imaging system is operated by a medical technician to acquire and record (e.g., tape) pertinent images of the body, while the doctor is not present to provide input as to the control settings of the system. Then, at a later time, the images are reviewed by the doctor who diagnoses the patient. The images are usually stored by the ultrasound imaging system as a video signal, or after the acoustic data has been fully processed and compressed by various signal processing stages and has reached the video stage within the signal processing pipeline associated with the ultrasound imaging system. The video signal is essentially comprised of a single or multiple planes of black and white picture elements (pixels) and/or color pixels.
A significant limitation of the foregoing methodology is that much of the information associated with the original ultrasound signal is not preserved, as the acoustic data has been processed by various mechanisms, such as filters, mixers, nonlinear transformations, compression mechanisms, etc., along the signal processing pipeline. Thus, when the images are reviewed, no additional or alternative signal processing may be performed upon the images by the doctor, and the patient is typically not available for more imaging sessions with the doctor.
An example of a commercially available ultrasound imaging system that generally employs the foregoing methodology is the Vingmed SD 100/200, which is a doppler-type system that is manufactured by Vingmed Corporation, U.S.A. The Vingmed SD 100/200 contains a frequency modulated (FM) video store capability, which provides for the storage and playback of baseband doppler audio. This signal, in the audio domain, is arguably analogous to visual information in the video domain. In other words, the stored signal is in the post-processed format, or the format in which it is presented to the user. Raw acoustic data is not preserved, and thus, additional and alternative signal processing of the ultrasound data cannot be performed. Only the stored baseband audio signal is available to the replay device.
Another example of a commercially available ultrasound imaging system is the SONOS.TM. 5500, which is manufactured by the Hewlett-Packard Company, USA. Hewlett-Packard's SONOS 5500 provides a slow motion video feature, called the "acoustic quick review" or just "quick review," which can review acoustic data in slow motion from the SONOS 5500 system. However, the information is stored to non-volatile memory as video pixel data, and is injected back into the system at the video stage of the system, which does not permit additional or alternate signal processing to be performed on the image data.
Thus, there is a heretofore unaddressed need in the industry for a better way to acquire and play back ultrasound images.